A number of techniques and devices have been developed for rebuilding or reconstruction of the acetabulum in a pelvis. It is the acetabulum into which the head of the femur fits to form the articulating hip joint. When undertaking a total or partial reconstruction of the hip joint, it is desirable to replicate the natural hip joint to the greatest degree possible. This means that the joint must be fully articulating, allowing a full range of normal movement of the femur relative to the pelvis. It is also necessary to ensure that any prosthesis used in the reconstruction will remain firmly in place after installation.
It is known to begin reconstruction of the acetabulum or socket by machining out the existing cavity to form a hemispherical cavity. A prosthetic cup is then installed into the new hemispherical cavity and usually cemented in place. The prosthetic cup will typically have an outer convex surface to conform to the hemispherical cavity and an inner concave surface to provide a new socket for the femoral head, or for a replacement femoral head. The prosthetic cup is held in place by the cement and by the natural process of ossification around the cup after installation.
These mechanisms result in varying degrees of success, depending upon the extent of deterioration of the existing pelvic bone and other factors. The cement can wear and loosen as a result of the repeated impact resulting from the normal use of the hip joint. In addition, further deterioration of the surrounding pelvic bone can severely reduce the available support for the prosthetic cup. Since the hip joint is often subjected to severe stress, the prosthetic cup can sometimes shift or even become dislodged, requiring further surgery and sometimes even causing further damage.
Therefore, it is an object of the present invention to provide a prosthetic cup for reconstruction of an acetabulum, which has a means of providing additional support from the pelvic bone. It is a further object of the present invention to provide an acetabular cup which receives much of its support from the inner portion of the pelvic structure relatively removed from the immediate acetabular cavity. It is yet another object of the present invention to provide a method of installing an acetabular cup which will result in support of the cup by an inner portion of the pelvic bone relatively removed from the acetabular cavity. Finally, it is an object of the present invention to provide an acetabular cup, and a method for its installation, which are easy and economical to construct and perform.